Capacitive deionization coupled with microbial fuel cells to desalinate low-concentration salt water

A new technology (CDI-MFC) that combined capacitive deionization (CDI) and microbial fuel cell (MFC) was developed to treat low-concentration salt water with NaCl concentration of 60 mg/L. The water desalination rate was 35.6 mg/(L h), meanwhile the charge efficiency was 21.8%. Two desorption modes were investigated: discharging (DC) mode and short circuit (SC) mode. The desalination rate in the DC mode was 200.6 ± 3.1 mg/(L h), 47.8% higher than that in the SC mode [135.7 ± 15.3 mg/(L h)]. The average current in the DC mode was also much higher than that of the SC mode. The energy stored in the CDI cell has been reused to enhance the electron production of MFC by the discharging desorption mode (DC mode), which offers an approach to recover the electrostatic energy in the CDI cell.